A PREDICTION BASED ALL—ZERO BLOCK DETECTION METHOD FOR H．263

In this letter,a novel method based on Temporal and Spatial Prediction(TSP)to detect all-zero DCT coefficients based on temporal and spatial prediction between neighboring blocks is proposed.The presented algorithm uses the knowledge of all-zero block distribution in the previous frame combined with the Sum of Absolute Difference(SAD)of the corresponding macroblock as a criterion .The algorithm almost needs no additional computation ,and it shows an excellent overall detection performance in simulations.     

双正交DCT在视频编码中的实现

采用仅有移位和加法操作的提升步长的双正交DCT变换来实现H.263视频压缩编码中的DCT变换。双正交DCT能快速有效地实现整数到整数的变换,在C6201定点DSP中,双正交DCT的编码速度与DCT相比有很大提高。     

移动视频通信的差错控制技术

移动信道是易错、窄带信道,而压缩视频对信道传输差错的影响比较敏感,因此,移动视频通信的差错控制技术成为一个研究热点。该文从信源编码、信道编码方面探讨了移动视频通信的差错控制技术,并用软件实现了H.263+压缩视频在瑞利衰落移动信道上的模拟传输及差错控制,验证移动视频通信差错控制技术的有效性和鲁棒性。     

H.263视频编码算法原理及DSP实现

介绍ITU-T H.263视频编码器在德州仪器（Texas Instruments)公司新一代数字信号处理芯片IMS320C6000上的实时实现技术。编程实现了H.263标准的主要内容及H.263 中提出的新的编码技术，重点讨论了H.263编码在TMS320C6711 DSP上的优化和实现。     

基于局域网实时视频代理的设计与实现

在基于以太网的数字视频监控系统中，设计了一个实时视频代理，详细描述了其协议设计、工作流程、启动配置、命令通道和环形缓冲区等关键技术。该视频代理实现了视频流的实时接收、录像、多路转发和报警。     

H.264视频编码标准及其在移动通信中的应用

H．264是ITU-T的视频编码专家组(VCEG)和ISO／IEC的活动图像专家组(MPEG)联合制定的视频编码新标准，其目的是为了获得很好的图像压缩效果并能适应不同的网络环境。从编码效率和网络适应性方面讨论了H．264中所采用的新技术，最后介绍了它在移动通信中的应用。     

基于XScale处理器的视频通信系统

主要介绍在基于XScale处理器(PXA255)的嵌入式开发平台上搭建视频通信原型系统的具体方法。整个系统共分为采集、显示、编码、解码、发送、接收6个功能模块,着重介绍视频编解码部分在嵌入式系统上的优化方法。实验结果表明,在基于XScale(PXA255)处理器的嵌入式系统平台上,该视频通信原型系统可以基本满足实时视频通信的要求,并具有良好的可扩展性。     

FPGA implementation of a HW/SW platform for multimedia embedded systems

This paper presents a HW/SW platform for embedded video system. It has been designed around an embedded RISC processor and FPGA technologies and provides video input and output interfaces. The configurable platform has been used to implement a real time video processing and vision systems. The Altera’s Nios II development board was chosen to realise this real time video platform which uses μClinux as embedded Linux Operating System. Experimental results using H.263 video encoder show that this platform provides enough resources and speed to implement even complex multimedia embedded systems in real time.     

High pressure/temperature treatments to inactivate highly infectious prion subpopulations

High hydrostatic pressure can be used for gentle pasteurization of food as well as a physical parameter to study the stability and energetics of biomolecules. High pressure has been recently postulated as a feasible technology to decontaminate scrapie infectious materials. Here we discuss the kinetic parameters driving the inactivation of the Transmissible Spongiform Encephalopathy agents and the perspectives of pressure as a thermodynamic parameter to obtain a deeper insight into the aggregation of the 263K strain of scrapie. At 60–80 °C an efficient pressure inactivation of infectious scrapie prions was observed during short pressure treatments at 800 MPa (3 × 5 min cycles). However, discrepancies between in vivo infectivity counts and the results of an enzyme immunoassay further revealed that the infectivity was inactivated faster and much more efficiently than PrP^res was degraded, indicating that pressure affects a highly infectious subpopulation of scrapie prions.

Industrial relevance

Conventional inactivation methods for the agents of the Transmissible Spongiform Encephalopathies are not compatible with food processing due to the required aggressive conditions. High pressure assisted thermal sterilization methods are nowadays attracting attention as a food preservation technology able to preserve quality attributes. Here the stark effects in the secondary prion structure of high pressure combined with heat below the usual denaturing conditions were investigated with specific tests. This technology was proven to be a feasible alternative to achieve the decontamination of TSE risk materials at milder conditions. Kinetic data provided here should be useful to establish criteria to inactivate prions under pressure.     

网络音像传输系统的软件设计-发送端

首先介绍了系统的方案,该方案采用G．729A标准和H．263标准分别对音频和视频数据进行压缩,并通过UDP协议对数据包进行网络传输。其次对系统的组成和工作流程做了简单概述,最后对语音传输系统中常见的问题,提出了相应的解决办法。